Abstracts

Juvenile myoclonic epilepsy (JME) is a syndrom of idiopathic generalized epilepsy (IGE) with an age-related onset. Absence of structural brain lesions is mandatory for the diagnosis of JME. However, the presence of typical, bifrontal accentuated epileptiform discharges has resulted in the hypothesis of frontal dysfunction. More recently, the use of sophisticated imaging seems to support this hypothesis. In addition, there is evidence for abnormal thalamo-cortical circuits in IGE. We examined the integrity of the white matter in JME patients using whole head diffusion tensor imaging (DTI)., Ten patients with JME were recruited from the epilepsy outpatient clinic of the University Hospital Muenster, Germany. Inclusion criteria were: 1) established diagnosis of JME, 2) no other neurological disease, 3) normal conventional MRI (1.5-Tesla scanner). The patients underwent MRI in a 3-Tesla scanner using the following sequences: volumetric T1-weighted, T2-weighted, Fluid attenuation inversion recovery (FLAIR), and DTI (20 gradient directions). Fractional anisotropy (FA) maps were calculated from DTI data to assess the white matter integrity. The results were compared on a voxel-by-voxel basis with data of an age-matched control group of 64 healthy volunteers (SPM5, two-sample t-test, treating the subjects[apos] age as [ldquo]effect of no interest[rdquo])., The age of the patients was 28[plusmn]8 years (Control group: 27.9, range 21[ndash]42 years) Age of epilepsy onset was 13.7[plusmn]2.6 years, the duration of the disease at the time of the scan was 14.2[plusmn]10.6 years. 7 of the patients had suffered 2-15 generalized tonic-clonic seizures (median: 9). All patients were under anticonvulsants (5 VPA monotherapy, 3 LTG monotherapy). The conventional imaging sequences (T1, T2, FLAIR) did not show any abnormalities. DTI revealed significantly reduced FA in thalamo-cortical, basal ganglia, parahippocampal and frontobasal fibers in JME patients compared to the control group (see figure). The severity of the frontal abnormalities was correlated to age, disease duration, treatment duration and number of generalized tonic-clonic seizures. These variables were strongly correlated to each other. However, the FA reduction remained significant even when controlled for the subjects[apos] age., Compared to healthy volunteers, JME patients seem to have reduced integrity of frontobasal, thalamo-cortical, basal ganglia, as well as parahippocampal fibers. It remains to be determined whether these abnormalities are related to the cause, the result or the treatment of the disease.[figure1],